Knife sharpening mechanism

ABSTRACT

A knife sharpening mechanism for a cutting machine having an elongated knife comprising a grinder carriage having a pair of legs each mounting an endless abrasive belt, a drive for driving the belts, a belt guiding shoe on each of the legs with each shoe mounting belt guide elements including guide blocks for pressing each endless belt into engagement with the edge of the knife to thereby grind a bevel on the knife, each of the belt guide elements being bendable so as to adjust the angle which each of the guide blocks makes with the edge of the knife, the belt guide elements also being sufficiently rigid to hold the guide blocks in the position to which they were last adjusted.

United States Patent 1191' Y i 1111: 3,775, 13

' Clark 1 Dec. 4, 1973 KNIFE SHARPENING MECHANISM Primary ExaminerD0nald 0. Kelly 75 I t. Fed kG.Cl kBffl,N.Y. 1 nven or r ar u a 0 Assistant Examinerl-loward N. Goldberg [73] A gn Eastman Machine C p y, Attorney-Kenneth R. Sommer et a].

Buffalo, NY.

[22] Filed: Nov. 3, 1971 [57] ABSTRACT 2 APPL 195 122 A knife sharpening mechanism for a cutting machine having an elongated knife comprising a grinder carriage having a pair of legs each mounting an endless [52] LS. Cl 51/246, 30/139, 5 i/l40 abrasive be a drive for driving the belts, a be id [51] [1 11. CI B241) 19/00 ing Shoe on each of the legs with Each Shoe mounting [58] Field of Search 51/246, 249, 140;

belt guide elements including guide blocks for pressing 30/138 139; 83/174 each endless belt into engagement with the edge of the knife to thereby grind a bevel on the knife, each of the [56] Reterences Cited belt guide elements being bendable so as to adjust the UNITED STATES PATENTS angle which each of the guide blocks makes with the 2,790,235 4/1957 Clark 30/139 g of the knife, the belt guide elements also being 3,547,607 12/1970 Bangser, Jr...

51/246 sufficiently rigid to hold the guide blocks in the posi- 2.737,763 3/1956 ry, Jr 51/246 tion to which theywere last adjusted.

3,350,818 11/1967 Clark 51/246 1 3,562,801 2 1971 Stucker 51/246 4 m 9 Drawing Flames LJ i 5 x 2?: 7a 6 7 344 19 1 ii ,q pn

PATENTEU sum 2 or 2.

ATTOHVEYS.

KNIFE SHARPENING MECHANISM The present invention relates to an improved knife sharpening mechanism for a cutting machine of the type commonly used for cutting cloth and other sheet materials and in which the cutting is effected by a reciprocatory knife.

By way of background, the knife of the foregoing type of machine must be sharpened periodically. The sharpening is effected by running a grinder carriage longitudinally of the knife, the carriage mounting a pair of endless belts which are held in grinding engagement with opposite sides of the knife. Periodically, it may be necessary to change the angle which the belts make with the knife so as to vary. the bevel on the edge of the knife. In the past the changing of the anglewas effected by adjusting the position of guide blocks, which backed up the belts, byloosening and tightening set screws which held th guide blocks in position. There were certain shortcomings to adjusting guide blocks in this manner, namely, that sometimes the set screws were not properly tightened so that the guide blocks became loose as a result of the vibration to which they were subjected with the attendant result that the knife edge was ground improperly. It is with overcoming the foregoing deficiency that the present invention is concerned.

It is accordingly the object of the present invention to provide an improved knife sharpening mechanism for a cloth cutting machine in which the blocks which adjust the angle which the grinding belts make with the knife can be adjusted in an extremely simple and expedient manner without the use of set screws or other movable connections which are subject, to becoming loose in operation. A related object of the present invention is to provide an improved knife sharpening mechanism for a cloth cutting machine which is cheaper and more reliable and more easily adjustable than prior known types of constructions. Other objects and attendant advantages of the present invention will be more readily perceived hereafter.

The improved knife sharpening mechanism of the present invention comprises a grinder carriage for movement longitudinally of an elongated knife, an abrasive knife sharpening belt on said carriage, means for moving said belt transversely relative to the edge of said knife to thus sharpen a bevel on said knife, a belt guiding shoe on said carraige, belt guide means on said belt guiding shoe including guide block means for pressing said belt into engagement with said knife, with said belt guide means being bendable to selectively vary the angle of said guide block means relative to said knife and also being sufficiently rigid to remain in the position to which it was bent.

The various aspects of the present invention will be more fully understood when the following portions of the specification are read in conjunction with the .accompanying drawings wherein:

FIG. 1 is a fragmentary side elevational view of a cutting machine having a carriage mounting the improved knife sharpening mechanism of the present invention;

FIG. 2 is a view, partially in cross section, taken sub stantially along line 2-2 of FIG. 1 and showing the knife sharpening carriage and related structure in plan;

FIG. 3 is a fragmentary cross sectional view taken substantially along line 3-3 of FIG. 1 and showing an enlarged detail the belt guides mounted on the carriage mounted shoes;

the upper shoe and belt guide;

FIG. .6 is a sideelevational view taken substantially in the direction of arrows 6-6 of FIG. 4 and showing the lower shoe and associated beltguide;

FIG. 7 is a perspective view of the belt guide shown in FIG. 6 and a tool for adjusting the angle of theguide block portion of thebelt guide;

FIG. 8 is a perspective view of the belt guide shown in FIG. and

FIG. 9. is a fragmentary cross sectional viewtaken substantially along line 9-9 of FIG. 2 and showing the structure for pivotally mounting the shoes on the carriage.

The improved knife sharpening mechanism 10 of the present invention is shown mounted on cutting machine 11, which may be similar to the one shown in greater detail in US. Pat. No. 2,790,235. Broadly machine 11 includes a base 12 having rollers 13 which roll on table top 14 which supports the lay of material to be cut. An uprightslender standard 15 is rigidly secured to base 12 and rises upwardly therefrom and supports the frame or housinglfi of an electric motor which, through a suitable drive arrangement (not shown), re-

ciprocates the knife. 17 mountedin vertical guide 18in standard 15. A presser foot 19 is mounted on the lower end of a guide bar 20 which extends vertically in front of the knife and is suitably mounted for vertical1 adjustment onthe machine to set the presser foot atdifferent levels according to the thickness of different lays or piles of material to be cut.

The knife 17 is sharpened by a grinding assemblyor sharpening mechanism 10 which includes a carriage 21 mounted at the lower end of .shaft22. Whenit is desired to cause carriage 21 toreciprocate along knife 17 to effect a knife sharpening operation, a suitable linkage (not shown) is actuated to cause shaft 22 to move downwardly out of housing 16 and thus carry carriage 21 with it. At the lowermost portion of its travel, carriage 21 will reverse and move upwardly due to the action of shaft 22 which has a double thread (not shown) thereon. A guide .bar 23 is received with a sliding fit in aperture 24 of carriage 21 to aid in stabilizing the car riage during its reciprocation.

Carriage 21 includes a pair of legs 25 and 26 which lieat differentelevations in substantially parallel planes and merge at their left ends into block 27 which is formed integrally therewith. Shafts 28 and 29, which are driven in opposite directions through suitable gearing driven by the motor within frame 16, have drive pulleys 30 and 31, respectively, affixed to the lower ends thereof. A first endless belt 32 of abrasive material encircles pulley 30 and pulley 33 joumalled on bracket 34 which is mounted for sliding; movement on leg 25 and biased tothe right in FIG. 2 by a spring 35 which is interposed between the end 36 of leg 25 and a tab 37 extending upwardly from the lower side 38 of the bracket 34, bracket 34 being held on leg 25 by tabs 39, 40 and 41 which are bent over the top of leg 25. A second endless abrasive belt 42 encircles drive pulley 31 and pulley 43 which is joumalled on bracket 44, which is a mirror image of bracket 34, and is mounted for sliding movement on leg 26 and is biased rearwardly by spring 45 which is analogous to spring 35. Screws 46 and 47 secured to legs 25 and 26, respectively, limit the longitudinal movement of brackets 34 and 44 in both directions because they are engaged by tabs such as 40 and 41.

Belts 32 and 42, which include a coating of suitable abrasive materiaL-are urged into contact with the opposite sides of knife 17 by guide block portions 48 and 49 which are formed at the ends of belt guides 50 and 51, respectively, the other ends of these belt guides including tabs 52 and 53, respectively, which are secured, as by welding or brazing in face to face relationship with the undersurfaces 53' and 54, respectively, of shoes 55 and 56, respectively. Guide block portions 48 and 49 have surfaces 57 and 58, respectively, thereon which are coatings of an abrasion-resistant material, such as I tungsten carbide or a hard ceramic material which will resist the wear produced by the rear surface of the abrasive belt passing across them. The surfaces 57 and 58 are on the order of three to four-thousandths of an inch thick and are applied by a suitable flame plating process.

Guide block portions 48 and 49 bias belts 32 and 42, respectively, into engagement with opposite sides of the knife to effect a sharpening of a bevel 59 thereon as the carriage 21 reciprocates vertically along the knife 17. This biasing is effected by springs 60 and 61 operatively associated with shoes 55 and 56, respec tively. More particularly, shoe 55 includes a body portion which is pivoted at its right end to leg 25 by pin 62 (FIG. 9) which is essentially a nut and bolt with the central portion63 of spring 60 interposed between the head of bolt 62 and a shoulder 64 on shoe 55. Spring 60 has one end affixed to carriage leg 25 at 66 and the other end extending into aperture 67 in shoe 55 so as to bias the shoe in a counterclockwise direction about pin 62 in FIG. 2. Spring 61 has an end secured to arm 26 at 68 and the other end mounted within aperture 69 in shoe 56 so as to bias the shoe in a clockwise direction in FIG. 2 about pin 62' which is analogous to pin 62 of FIG. 9.

As noted briefly above, it can readily be appreciated therefore that belts 32 and 42 are driven by shafts 28 and 29, respectively, so as to grind a bevel on knife 17 as a carriage 21 is reciprocated longitudinally thereof.

In accordance with the present invention guide portions 48 and 49 of belt guides 50 and 51, respectively, are bendable toward or away from the knife edge 59 to provide a short or long bevel, as desired. More specifically by means of a tool having an end portion 70 with a slot 71 (FIG. 7) guide block portions 48 or 49 may be engaged and these guide block portions may be bent relative to the body portions of the belt guides to adjust the angle which they make with the edge of the knife. Belt guides 50 and 51 are made of a relatively ductile metal, for example, 18 gauge dead soft cold rolled steel. Other suitable materials may also be used. The basic requirement is that the material forming guides 50 and 51 has sufficient flexibility or bendability to withstand bending to a position in the range of to in either direction from a preset central position without breaking and at the same time to be capable of withstanding the spring pressure applied by springs 60 and 61 without bending out of position. The desired flexibility of the belt guides 50 and 51 can be controlled through the choice of a suitable material, thickness of the material, and/or by varying the width of the material designated by dimension 73 (FIG. 8) at the fulcrum point or bending area 72 about which bending occurs. The advantage of having a bendable belt guide construction such as shown at 50 and 51 is that the guide block portions 48 and 49 will remain in any adjusted position regardless of the amount of vibration to which carriage 21 is subjected, whereas this is not the case in constructions utilizing set screws or the like for effecting the adjustment, inasmuch as set screws could vibrate loose. Furthermore, the belt guides 50 and 51 cannot be tampered with, that is removed from the shoes 55 and 56 inasmuch as they are welded or brazed thereto, as discussed in detail above. Furthermore, in view of the fact that the belt guides 50 and 51 are integrally attached to the shoes 55 and 56, the overall construction is cheaper and more reliable.

Shoes 55 and 56 have vertically extending portions 75 and 76, respectively, which carry set screws 77 and 78, respectively. These set screws are adjusted relative to knife 17 by means of a feeler gauge so that they have a predetermined clearance relative to the knife. In the event for any reason the belts 42 or 32 should drop below the lower end of knife 17, set screws 77 and 78 will engage the knife so as to prevent the belt guides 50 and 51 from snagging on knife 17 during the return travel of carriage 21.

Additional structure is provided to prevent guide block portion 48 from moving underneath and snagging on the lower end of knife 17 whenever it moves below the lower end of the knife. In this respect, portion 75 of shoe 55 terminates at finger portion 79 which in cooperation with the serrations 80 on pivotal arm 81 forms a detent arrangement whereby serrations 80 permit portion 75 to move away from knife 17, as required without permitting it to move toward the knife, except when it is reset at the uppermost portion of a stroke by a cam arrangement (not shown). More specifically, arm 81 (FIG. 2) is pivotally'mounted at 82 on bracket 83 and is biased in a counterclockwise direction by spring 84 having end 85 secured to arm 81 and end 86 beating against block 27 of the carriage. Thus arm 81 is biased into engagement with finger portion 79 to prevent shoe 55 and guide block portion 49 from moving toward knife 17 while permitting it to yield away therefrom if a predetermined force of contact between belt 32 and knife 17 is exceeded. This subject matter, which forms no part of the present invention, is described in greater detail in applicants application Ser. No. 162,922 filed July 15, 1971, now US. Pat. No.

It can thus be seen that the above described knife sharpening mechanism is manifestly capable of achieving the above enumerated objects and while a preferred embodiment has been disclosed, it will be appreciated that it can otherwise be embodied within the scope of the following claims.

What is claimed is:

1. A knife sharpening mechanism for a cutting machine having an elongated knife comprising a grinder carriage for movement longitudinally of said knife, an abrasive knife sharpening belt on said carriage, means for moving said belt relative to the edge of said knife to thus sharpen a bevel on said knife, belt guide means on said carriage including guide block means for pressing said belt into engagement with said knife, said belt guide means being bendable in a direction substantially parallel to said bevel to selectively vary the angle of said guide block means relative to said knife and also being sufficiently rigid to remain in the position in which it was last bent, a shoe for mounting said belt guide means, said belt guide means including first and second end portions integral with a body portion, with said first end portion being permanently bonded to said shoe and said second end portion being free and unattached relative to said shoe, said guide block means forming said second end portion, and a bending area on said body portion.

2. A knife sharpening mechanism for a cutting ma chine having an elongated knife as set forth in claim 1 wherein said first end portion comprises a horizontal tab and wherein said guide block. means comprises a vertically oriented block-like portion.

3. A knife sharpening mechanism for a cutting ma each mounting a shoe and belt guide means thereon. 

1. A knife sharpening mechanism for a cutting machine having an elongated knife comprising a grinder carriage for movement longitudinally of said knife, an abrasive knife sharpening belt on said carriage, means for moving said belt relative to the edge of said knife to thus sharpen a bevel on said knife, belt guide means on said carriage including guide block means for pressing said belt into engagement with said knife, said belt guide means being bendable in a direction substantially parallel to said bevel to selectively vary the angle of said guide block means relative to said knife and also being sufficiently rigid to remain in the position in which it was last bent, a shoe for mounting said belt guide means, said belt guide means including first and second end portions integral with a body portion, with said first end portion being permanently bonded to said shoe and said second end portion being free and unattached relative to said shoe, said guide block means forming said second end portion, and a bending area on said body portion.
 2. A knife sharpening mechanism for a cutting machine having an elongated knife as set forth in claim 1 wherein said first end portion comprises a horizontal tab and wherein said guide block means comprises a vertically oriented block-like portion.
 3. A knife sharpening mechanism for a cutting machine having an elongated knife As set forth in claim 2 wherein said body portion is located between said first and second ends, and wherein said bending area is vertically oriented in said body portion and said guide block means is pivotable about said bending area.
 4. A knife sharpening mechanism for a cutting machine having an elongated knife as set forth in claim 1 wherein said carriage includes first and second legs each mounting a shoe and belt guide means thereon. 